In today’s gadget-obsessed society, Blackberrys and flip phones are often derided as being clunky and old-fashioned, thanks to their push-button keypads, low-resolution screens, and stop-and-go web browsing.

People with older phones who can do without the latest features may now have a better reason to consider upgrading: According to new research, Blackberrys and flip phones are more likely than newer touch-screen models to contain nickel, a metal that can trigger an eczema-like rash in some people.

Allergists and dermatologists first noticed phone-related skin problems about 10 years ago, when patients began trickling into their offices with patches of dry, itchy, red, or swollen skin along their cheekbones, jawlines, and ears. These rashes, the doctors soon figured out, tended to clear up on their own if the patients stopped using a cell phone.

Numerous case reports have since linked cell phones to nickel allergy, which affects an estimated 17% of women and 3% of men. Skin problems associated with the allergy are usually triggered by earrings and other jewelry (which likely explains the higher rate in women), as well as by watchbands, belt buckles, dental fillings, and makeup.

To determine whether some phones might be more aggravating than others, researchers at the Winthrop-University Hospital, in Mineola, N.Y., tested a total of 72 phones spanning five brands and 16 different models. The researchers swabbed the exterior of each phone with a special nickel-detecting solution in at least five places, such as the keypad and speakers.

Not one of the iPhone or Droid models tested positive for nickel, whereas the metal was found on roughly 30% of Blackberrys and 90% of flip phones—including all six of the Samsung and all nine of the LG phones tested. Cobalt, another metal that can trigger allergies, also was more common on flip phones, though it was less prevalent than nickel overall.

Phone manufacturers “are using lighter materials now, and a lot more plastic casings and copper to make things look fancy and pretty,” says Luz Fonacier, MD, head of the hospital’s allergy department and an associate professor of clinical medicine at Stony Brook University, in Stony Brook, N.Y. “For people with nickel allergies, this just happens to be a good thing.”

More than 230 million people in the United States now use mobile phones. Nickel can be found in the electronic innards of nearly every phone, but it’s also sometimes used as an exterior design element, often around buttons and keypads. That may explain the lack of detectable nickel in touch-screen iPhones and Droid phones, Fonacier says.

Jeannette Graf, MD, a dermatologist at the Mount Sinai School of Medicine, in New York City, says cell phone allergies are “extremely rare” but not unheard of in people who have experienced reactions to nickel in the past.

“It is possible to have dryness and rash without realizing what the cause is,” Graf says. “But it would be unusual to see it from a cell phone without seeing it from earrings or on the belt line where jeans are buttoned, at the same time.”

Nickel isn’t always to blame for skin issues, Graf adds. In some cases, she says, long hours on the phone can cause rash-like symptoms stemming from skin irritation or clogged pores.

Cell phone users who suspect they might be experiencing a nickel allergy should see their doctor—and if necessary an allergist—for proper testing and diagnosis, Fonacier says. Simple remedies such as choosing a different phone, using a wireless earpiece, or buying a plastic case for an existing phone may be enough to prevent nickel-related rashes, she says.

Fonacier presented the test results today at the annual meeting of the American College of Allergy, Asthma and Immunology, a professional association for allergists. Unlike the research published in medical journals, the study has yet to be thoroughly vetted by other experts in the field.